I'm having the same error, showing that the users and samba modules fail to start. Going through the web-based manager, I get the identical - "failed to connect to ldap" error.
The ebox.log file shows a pile of "Ldap.pm:112x Ebox::Ldap::safeConnect - Couldn't connect to LDAP server" errors.
Wierdly, everything was working fine, and then I installed a second server running an identical configuration of Zentyal on the server (to see if I could run two file servers at the same time, but not in a Master / Slave type configuration).
As soon as both boxes were put on line, sharing stopped working, and straight logging into the boxes normally (i.e. through a shell) or turning root takes forever at the password validation stage. This got me thinking there is an LDAP issue.
I've removed both servers from the network, restarted them while disconnected, and logons through shell are still long (+30 seconds). I figured maybe it was a dns lookup issue ... but with the box disconnected there should be no place to look further right?
Running "ps aux | grep slapd" indicates slapd is running, but running "/etc/init.d/ebox restart" shows the Zentyal restarts everything except "users" and "samba"
I should add I also ran "/etc/init.d/slapd restart" prior to restarting ebox...
Any suggestions? This is the latest Zentyal running on Ubuntu 11.04 ...